Considering the influence of temperature on the oil viscosity of the yaw damper,the influence of oil temperature on the dynamic performances of high speed vehicles was analyzed based on SIMPACK.It is found that the critical speed is increased as the temperature decreases in the proper range of oil temperature,and low temperature has a larger influence on the vehicle stability than high temperature because of the relationship between oil viscosity and temperature.The oil temperature has few influence on vehicle stationary when the vehicle speed is less than 200 km/h,however it has a certain effect on vehicle stationary and the effect is increased with the vehicle speed when the vehicle speed exceeds 200 km/h.The oil temperature has few effect on the safety of the vehicle.